A controlled clinical study of the effect of nasal immunization with a Streptococcus mutans antigen alone or incorporated into liposomes on inductionof immune responses

Recent attention to mucosal immunization strategies has been focused on the nasal route for vaccine delivery. This study was designed to determine the effectiveness of a liposome-protein vaccine compared to that of a protein- only vaccine in inducing immune responses in humans. Wealthy subjects were randomly assigned to two groups and immunized intranasally with a crude ant igen preparation rich in glucosyltransferase (C-GTF) from Streptococcus mut ans, alone or in liposomes. Parotid saliva, nasal wash, and serum were coll ected prior to and at weekly intervals following immunization and were anal yzed for anti-C-GTF activity by enzyme-linked immunosorbent assay. The leve ls of immunoglobulin A (IgA) anti-C-GTF activity in the nasal wash from bot h groups after immunization increased to a mean peak of fivefold over the b aseline level on day 28, Salivary IgA anti-C-GTF responses mere induced to a lesser extent. IgG and IgA anti-C-GTF responses in serum were detected on day 14. The IgA responses were predominantly of the IgA1 subclass. These r esults show that C-GTF vaccines were more effective in inducing a local sec retory IgA antibody response than a salivary or serum response when they we re given intranasally. The IgA1 anti-C-GTF response in nasal wash samples f or liposomal antigen versus antigen only was the only response which was si gnificantly different (P < 0.04), This suggests that the form of the antige n affects the magnitude of the local mucosal response but not that of a dis seminated response. These results provide evidence for the effective use of a nasal protein vaccine in humans for the induction of mucosal and systemi c responses.